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roiAlignPlugin

README.md

ROIAlign

Table Of Contents

Description

The ROIAlign plugin implements the Region of Interest (RoI) align operation described in the Mask R-CNN paper, in compliance with the ONNX specification for the same (insofar as TRT limitations allow).

Structure

This plugin has the plugin creator class ROIAlignPluginCreator and the plugin class ROIAlign which extends IPluginV2DynamicExt.

The RoiAlign plugin consumes the following inputs:

  1. X with shape (batch_size, C, height, width): An input tensor.
  2. rois with shape (num_rois, 4): Regions of interest (ROIs).
  3. batch_indices with shape (num_rois,): The set of indices in X to apply pooling. i.e. The ROI defined by rois[i], should be used to pool X[batch_indices[i]].

The RoiAlign plugin produces the following output:

  1. Y with shape (num_rois, C, output_height, output_width): Y[i] is the output produced when pooling is applied over the ROI defined by rois[i] on X[batch_indices[i]].

Parameters

The ROIAlign plugin has the following parameters:

Type Parameter Description
int coordinate_transformation_mode Whether or not the input coordinates should be shifted by 0.5 pixels. Allowed values are 0 and 1. Default is 1 and indicates a shift.
int mode The pooling method. Average pooling (indicated by 1) and max pooling (indicated by 0) are supported. Allowed values are 0 and 1. Default is 1.
int output_height Height of the pooled output (Y). Allowed values are positive integers. Default is 1.
int output_width Width of the pooled output (Y). Allowed values are positive integers. Default is 1.
int sampling_ratio Number of sampling points in the interpolation grid used to compute the output value of each pooled output bin. If positive, then exactly sampling_ratio x sampling_ratio grid points are used. If zero, then an adaptive number of grid points are used (computed as ceil(roi_width / output_width), and likewise for height). Allowed values are non-negative integers. Default is 0.
float spatial_scale Multiplicative factor used to translate the ROI coordinates from their input spatial scale to the scale used when pooling. Allowed values are positive. Default is 1.0.

Additional resources

The following resources provide a deeper understanding of the ROIAlign plugin:

License

For terms and conditions for use, reproduction, and distribution, see the TensorRT Software License Agreement documentation.

Changelog

June 2022: This is the first release of this README.md file.

Known issues

There are no known issues in this plugin.